X-Git-Url: http://git.vpit.fr/?a=blobdiff_plain;ds=sidebyside;f=lib%2FScope%2FUpper.pm;h=1ae9f9c7f117c9b6948e8ff61c79abeda2eff4c3;hb=b143b5ed4d9b116054d12ea0696167b6a199b500;hp=51560158b054cb9532ebacbeb1b131fe34bed065;hpb=0a6221d3f467b5f819e3c119b4cda0218399cb51;p=perl%2Fmodules%2FScope-Upper.git
diff --git a/lib/Scope/Upper.pm b/lib/Scope/Upper.pm
index 5156015..1ae9f9c 100644
--- a/lib/Scope/Upper.pm
+++ b/lib/Scope/Upper.pm
@@ -9,60 +9,92 @@ Scope::Upper - Act on upper scopes.
=head1 VERSION
-Version 0.05
+Version 0.19
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.05';
+ $VERSION = '0.19';
}
=head1 SYNOPSIS
- package X;
+L, L, L, L and L :
- use Scope::Upper qw/reap localize localize_elem localize_delete UP/;
+ package Scope;
- sub desc { shift->{desc} }
+ use Scope::Upper qw<
+ reap localize localize_elem localize_delete
+ :words
+ >;
- sub set_tag {
- my ($desc) = @_;
+ sub new {
+ my ($class, $name) = @_;
- # First localize $x so that it gets destroyed last
- localize '$x' => bless({ desc => $desc }, __PACKAGE__) => UP;
+ localize '$tag' => bless({ name => $name }, $class) => UP;
- reap sub {
- my $pkg = caller;
- my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope
- print $x->desc . ": done\n";
- } => UP;
+ reap { print Scope->tag->name, ": end\n" } UP;
+ }
+
+ # Get the tag stored in the caller namespace
+ sub tag {
+ my $l = 0;
+ my $pkg = __PACKAGE__;
+ $pkg = caller $l++ while $pkg eq __PACKAGE__;
+
+ no strict 'refs';
+ ${$pkg . '::tag'};
+ }
+
+ sub name { shift->{name} }
+ # Locally capture warnings and reprint them with the name prefixed
+ sub catch {
localize_elem '%SIG', '__WARN__' => sub {
- my $pkg = caller;
- my $x = do { no strict 'refs'; ${$pkg.'::x'} }; # Get the $x in the scope
- CORE::warn($x->desc . ': ' . join('', @_));
+ print Scope->tag->name, ': ', @_;
} => UP;
+ }
- localize_delete '@ARGV', $#ARGV => UP; # delete last @ARGV element
+ # Locally clear @INC
+ sub private {
+ for (reverse 0 .. $#INC) {
+ # First UP is the for loop, second is the sub boundary
+ localize_delete '@INC', $_ => UP UP;
+ }
}
- package Y;
+ ...
+
+ package UserLand;
{
- X::set_tag('pie');
- # $x is now a X object, and @ARGV has one element less
- warn 'what'; # warns "pie: what at ..."
- ...
- } # "pie: done" is printed
+ Scope->new("top"); # initializes $UserLand::tag
+
+ {
+ Scope->catch;
+ my $one = 1 + undef; # prints "top: Use of uninitialized value..."
- package Z;
+ {
+ Scope->private;
+ eval { require Cwd };
+ print $@; # prints "Can't locate Cwd.pm in @INC
+ } # (@INC contains:) at..."
- use Scope::Upper qw/unwind want_at :words/;
+ require Cwd; # loads Cwd.pm
+ }
+
+ } # prints "top: done"
+
+L and L :
+
+ package Try;
+
+ use Scope::Upper qw;
sub try (&) {
my @result = shift->();
- my $cx = SUB UP SUB;
+ my $cx = SUB UP; # Point to the sub above this one
unwind +(want_at($cx) ? @result : scalar @result) => $cx;
}
@@ -70,55 +102,94 @@ BEGIN {
sub zap {
try {
+ my @things = qw;
return @things; # returns to try() and then outside zap()
- }
+ # not reached
+ };
+ # not reached
}
- my @what = zap(); # @what contains @things
+ my @stuff = zap(); # @stuff contains qw
+ my $stuff = zap(); # $stuff contains 3
-=head1 DESCRIPTION
+L :
-This module lets you defer actions that will take place when the control flow returns into an upper scope.
-Currently, you can hook an upper scope end, or localize variables, array/hash values or deletions of elements in higher contexts.
-You can also return to an upper level and know which context was in use then.
+ package Uplevel;
-=head1 WORDS
+ use Scope::Upper qw;
-These control words are to be used to indicate the target scope.
+ sub target {
+ faker(@_);
+ }
-=head2 C
+ sub faker {
+ uplevel {
+ my $sub = (caller 0)[3];
+ print "$_[0] from $sub()";
+ } @_ => CALLER(1);
+ }
-Returns the level that currently represents the highest scope.
+ target('hello'); # "hello from Uplevel::target()"
-=head2 C
+L and L :
-The current level.
+ use Scope::Upper qw;
-=head2 C
+ my $uid;
-The level of the scope just above C<$from>.
+ {
+ $uid = uid();
+ {
+ if ($uid eq uid(UP)) { # yes
+ ...
+ }
+ if (validate_uid($uid)) { # yes
+ ...
+ }
+ }
+ }
+
+ if (validate_uid($uid)) { # no
+ ...
+ }
+
+=head1 DESCRIPTION
-=head2 C
+This module lets you defer actions I that will take place when the control flow returns into an upper scope.
+Currently, you can:
-The level of the scope just below C<$from>.
+=over 4
+
+=item *
-=head2 C
+hook an upper scope end with L ;
-The level of the closest subroutine context above C<$from>.
+=item *
-=head2 C
+localize variables, array/hash values or deletions of elements in higher contexts with respectively L, L and L ;
-The level of the closest eval context above C<$from>.
+=item *
-If C<$from> is omitted in any of those functions, the current level is used as the reference level.
+return values immediately to an upper level with L, and know which context was in use then with L ;
-=head2 C
+=item *
-The level of the C<$stack>-th upper subroutine/eval/format context.
-It kind of corresponds to the context represented by C, but while e.g. C refers to the caller context, C will refer to the top scope in the current context.
+execute a subroutine in the setting of an upper subroutine stack frame with L ;
+
+=item *
+
+uniquely identify contextes with L and L.
+
+=back
=head1 FUNCTIONS
+In all those functions, C<$context> refers to the target scope.
+
+You have to use one or a combination of L to build the C<$context> passed to these functions.
+This is needed in order to ensure that the module still works when your program is ran in the debugger.
+The only thing you can assume is that it is an I indicator of the frame, which means that you can safely store it at some point and use it when needed, and it will still denote the original scope.
+
=cut
BEGIN {
@@ -126,13 +197,20 @@ BEGIN {
XSLoader::load(__PACKAGE__, $VERSION);
}
-=head2 C
+=head2 C
+
+ reap { ... };
+ reap { ... } $context;
+ &reap($callback, $context);
+
+Adds a destructor that calls C<$callback> (in void context) when the upper scope represented by C<$context> ends.
-Add a destructor that calls C<$callback> when the C<$level>-th upper scope ends, where C<0> corresponds to the current scope.
+=head2 C
-=head2 C
+ localize $what, $value;
+ localize $what, $value, $context;
-A C delayed to the time of first return into the C<$level>-th upper scope.
+Introduces a C delayed to the time of first return into the upper scope denoted by C<$context>.
C<$what> can be :
=over 4
@@ -154,24 +232,47 @@ For example,
will set C<$x> to a reference to the string C<'foo'>.
Other sigils (C<'@'>, C<'%'>, C<'&'> and C<'*'>) require C<$value> to be a reference of the corresponding type.
-When the symbol is given by a string, it is resolved when the actual localization takes place and not when C is called.
-This means that
+When the symbol is given by a string, it is resolved when the actual localization takes place and not when L is called.
+Thus, if the symbol name is not qualified, it will refer to the variable in the package where the localization actually takes place and not in the one where the L call was compiled.
+For example,
- sub tag { localize '$x', $_[0] => UP }
+ {
+ package Scope;
+ sub new { localize '$tag', $_[0] => UP }
+ }
+
+ {
+ package Tool;
+ {
+ Scope->new;
+ ...
+ }
+ }
-will localize in the caller's namespace.
+will localize C<$Tool::tag> and not C<$Scope::tag>.
+If you want the other behaviour, you just have to specify C<$what> as a glob or a qualified name.
+
+Note that if C<$what> is a string denoting a variable that wasn't declared beforehand, the relevant slot will be vivified as needed and won't be deleted from the glob when the localization ends.
+This situation never arises with C because it only compiles when the localized variable is already declared.
+Although I believe it shouldn't be a problem as glob slots definedness is pretty much an implementation detail, this behaviour may change in the future if proved harmful.
=back
-=head2 C
+=head2 C
+
+ localize_elem $what, $key, $value;
+ localize_elem $what, $key, $value, $context;
-Similar to L but for array and hash elements.
-If C<$what> is a glob, the slot to fill is determined from which type of reference C<$value> is ; otherwise it's inferred from the sigil.
+Introduces a C or C delayed to the time of first return into the upper scope denoted by C<$context>.
+Unlike L, C<$what> must be a string and the type of localization is inferred from its sigil.
+The two only valid types are array and hash ; for anything besides those, L will throw an exception.
C<$key> is either an array index or a hash key, depending of which kind of variable you localize.
-=head2 C
+If C<$what> is a string pointing to an undeclared variable, the variable will be vivified as soon as the localization occurs and emptied when it ends, although it will still exist in its glob.
+
+=head2 C
-Similiar to L, but for deleting variables or array/hash elements.
+Introduces the deletion of a variable or an array/hash element delayed to the time of first return into the upper scope denoted by C<$context>.
C<$what> can be:
=over 4
@@ -192,48 +293,342 @@ C<$key> is ignored.
=back
-=head2 C
+=head2 C
-Returns C<@values> I the context indicated by C<$level>, i.e. from the subroutine, eval or format just above C<$level>.
+ unwind @values;
+ unwind @values, $context;
-The upper level isn't coerced onto C<@values>, which is hence always evaluated in list context.
+Returns C<@values> I the context pointed by C<$context>, i.e. from the subroutine, eval or format at or just above C<$context>, and immediately restart the program flow at this point - thus effectively returning to an upper scope.
+
+The upper context isn't coerced onto C<@values>, which is hence always evaluated in list context.
This means that
my $num = sub {
my @a = ('a' .. 'z');
unwind @a => HERE;
+ # not reached
}->();
will set C<$num> to C<'z'>.
You can use L to handle these cases.
-=head2 C
+=head2 C
+
+ my $want = want_at;
+ my $want = want_at $context;
-Like C, but for the subroutine/eval/format context just above C<$level>.
+Like C, but for the subroutine/eval/format at or just above C<$context>.
The previous example can then be "corrected" :
my $num = sub {
my @a = ('a' .. 'z');
unwind +(want_at(HERE) ? @a : scalar @a) => HERE;
+ # not reached
}->();
-will righteously set C<$num> to C<26>.
+will rightfully set C<$num> to C<26>.
+
+=head2 C
+
+ my @ret = uplevel { ...; return @ret };
+ my @ret = uplevel { my @args = @_; ...; return @ret } @args;
+ my @ret = uplevel { ... } @args, $context;
+ my @ret = &uplevel($callback, @args, $context);
+
+Executes the code reference C<$code> with arguments C<@args> as if it were located at the subroutine stack frame pointed by C<$context>, effectively fooling C and C into believing that the call actually happened higher in the stack.
+The code is executed in the context of the C call, and what it returns is returned as-is by C.
+
+ sub target {
+ faker(@_);
+ }
+
+ sub faker {
+ uplevel {
+ map { 1 / $_ } @_;
+ } @_ => CALLER(1);
+ }
+
+ my @inverses = target(1, 2, 4); # @inverses contains (0, 0.5, 0.25)
+ my $count = target(1, 2, 4); # $count is 3
+
+L also implements a pure-Perl version of C.
+Both are identical, with the following caveats :
+
+=over 4
+
+=item *
+
+The L implementation of C may execute a code reference in the context of B upper stack frame.
+The L version can only uplevel to a B stack frame, and will croak if you try to target an C or a format.
+
+=item *
+
+Exceptions thrown from the code called by this version of C will not be caught by C blocks between the target frame and the uplevel call, while they will for L's version.
+This means that :
+
+ eval {
+ sub {
+ local $@;
+ eval {
+ sub {
+ uplevel { die 'wut' } CALLER(2); # for Scope::Upper
+ # uplevel(3, sub { die 'wut' }) # for Sub::Uplevel
+ }->();
+ };
+ print "inner block: $@";
+ $@ and exit;
+ }->();
+ };
+ print "outer block: $@";
+
+will print "inner block: wut..." with L and "outer block: wut..." with L.
+
+=item *
+
+L globally overrides the Perl keyword C, while L does not.
+
+=back
+
+A simple wrapper lets you mimic the interface of L :
+
+ use Scope::Upper;
+
+ sub uplevel {
+ my $frame = shift;
+ my $code = shift;
+ my $cxt = Scope::Upper::CALLER($frame);
+ &Scope::Upper::uplevel($code => @_ => $cxt);
+ }
+
+Albeit the three exceptions listed above, it passes all the tests of L.
+
+=head2 C
+
+ my $uid = uid;
+ my $uid = uid $context;
+
+Returns an unique identifier (UID) for the context (or dynamic scope) pointed by C<$context>, or for the current context if C<$context> is omitted.
+This UID will only be valid for the life time of the context it represents, and another UID will be generated next time the same scope is executed.
+
+ my $uid;
+
+ {
+ $uid = uid;
+ if ($uid eq uid()) { # yes, this is the same context
+ ...
+ }
+ {
+ if ($uid eq uid()) { # no, we are one scope below
+ ...
+ }
+ if ($uid eq uid(UP)) { # yes, UP points to the same scope as $uid
+ ...
+ }
+ }
+ }
+
+ # $uid is now invalid
+
+ {
+ if ($uid eq uid()) { # no, this is another block
+ ...
+ }
+ }
+
+For example, each loop iteration gets its own UID :
+
+ my %uids;
+
+ for (1 .. 5) {
+ my $uid = uid;
+ $uids{$uid} = $_;
+ }
+
+ # %uids has 5 entries
+
+The UIDs are not guaranteed to be numbers, so you must use the C operator to compare them.
+
+To check whether a given UID is valid, you can use the L function.
+
+=head2 C
+
+ my $is_valid = validate_uid $uid;
+
+Returns true if and only if C<$uid> is the UID of a currently valid context (that is, it designates a scope that is higher than the current one in the call stack).
+
+ my $uid;
+
+ {
+ $uid = uid();
+ if (validate_uid($uid)) { # yes
+ ...
+ }
+ {
+ if (validate_uid($uid)) { # yes
+ ...
+ }
+ }
+ }
+
+ if (validate_uid($uid)) { # no
+ ...
+ }
+
+=head1 CONSTANTS
+
+=head2 C
+
+True iff the module could have been built when thread-safety features.
+
+=head1 WORDS
+
+=head2 Constants
+
+=head3 C
+
+ my $top_context = TOP;
+
+Returns the context that currently represents the highest scope.
+
+=head3 C
+
+ my $current_context = HERE;
+
+The context of the current scope.
+
+=head2 Getting a context from a context
+
+For any of those functions, C<$from> is expected to be a context.
+When omitted, it defaults to the the current context.
+
+=head3 C
+
+ my $upper_context = UP;
+ my $upper_context = UP $from;
+
+The context of the scope just above C<$from>.
+
+=head3 C
+
+ my $sub_context = SUB;
+ my $sub_context = SUB $from;
+
+The context of the closest subroutine above C<$from>.
+Note that C<$from> is returned if it is already a subroutine context ; hence C.
+
+=head3 C
+
+ my $eval_context = EVAL;
+ my $eval_context = EVAL $from;
+
+The context of the closest eval above C<$from>.
+Note that C<$from> is returned if it is already an eval context ; hence C.
+
+=head2 Getting a context from a level
+
+Here, C<$level> should denote a number of scopes above the current one.
+When omitted, it defaults to C<0> and those functions return the same context as L.
+
+=head3 C
+
+ my $context = SCOPE;
+ my $context = SCOPE $level;
+
+The C<$level>-th upper context, regardless of its type.
+
+=head3 C
+
+ my $context = CALLER;
+ my $context = CALLER $level;
+
+The context of the C<$level>-th upper subroutine/eval/format.
+It kind of corresponds to the context represented by C, but while e.g. C refers to the caller context, C will refer to the top scope in the current context.
+
+=head2 Examples
+
+Where L fires depending on the C<$cxt> :
+
+ sub {
+ eval {
+ sub {
+ {
+ reap \&cleanup => $cxt;
+ ...
+ } # $cxt = SCOPE(0) = HERE
+ ...
+ }->(); # $cxt = SCOPE(1) = UP = SUB = CALLER(0)
+ ...
+ }; # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1)
+ ...
+ }->(); # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2)
+ ...
+
+Where L, L and L act depending on the C<$cxt> :
+
+ sub {
+ eval {
+ sub {
+ {
+ localize '$x' => 1 => $cxt;
+ # $cxt = SCOPE(0) = HERE
+ ...
+ }
+ # $cxt = SCOPE(1) = UP = SUB = CALLER(0)
+ ...
+ }->();
+ # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1)
+ ...
+ };
+ # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2)
+ ...
+ }->();
+ # $cxt = SCOPE(4), UP SUB UP SUB = UP SUB EVAL = UP CALLER(2) = TOP
+ ...
+
+Where L, L and L point to depending on the C<$cxt>:
+
+ sub {
+ eval {
+ sub {
+ {
+ unwind @things => $cxt; # or uplevel { ... } $cxt;
+ ...
+ }
+ ...
+ }->(); # $cxt = SCOPE(0) = SCOPE(1) = HERE = UP = SUB = CALLER(0)
+ ...
+ }; # $cxt = SCOPE(2) = UP UP = UP SUB = EVAL = CALLER(1) (*)
+ ...
+ }->(); # $cxt = SCOPE(3) = SUB UP SUB = SUB EVAL = CALLER(2)
+ ...
+
+ # (*) Note that uplevel() will croak if you pass that scope frame,
+ # because it cannot target eval scopes.
=head1 EXPORT
-The functions L, L, L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>.
+The functions L, L, L, L, L, L and L are only exported on request, either individually or by the tags C<':funcs'> and C<':all'>.
-Same goes for the words L, L, L, L, L, L and L that are only exported on request, individually or by the tags C<':words'> and C<':all'>.
+The constant L is also only exported on request, individually or by the tags C<':consts'> and C<':all'>.
+
+Same goes for the words L, L, L, L, L, L and L that are only exported on request, individually or by the tags C<':words'> and C<':all'>.
=cut
-use base qw/Exporter/;
+use base qw;
our @EXPORT = ();
our %EXPORT_TAGS = (
- funcs => [ qw/reap localize localize_elem localize_delete unwind want_at/ ],
- words => [ qw/TOP HERE UP DOWN SUB EVAL CALLER/ ],
+ funcs => [ qw<
+ reap
+ localize localize_elem localize_delete
+ unwind want_at
+ uplevel
+ uid validate_uid
+ > ],
+ words => [ qw ],
+ consts => [ qw ],
);
our @EXPORT_OK = map { @$_ } values %EXPORT_TAGS;
$EXPORT_TAGS{'all'} = [ @EXPORT_OK ];
@@ -260,8 +655,35 @@ Consider those examples:
The first case is "solved" by moving the C before the C, and the second by using L instead of L.
-L, L and L effects can't cross C blocks, hence calling those functions in C is deemed to be useless.
+The effects of L, L and L can't cross C blocks, hence calling those functions in C is deemed to be useless.
This is an hopeless case because C blocks are executed once while localizing constructs should do their job at each run.
+However, it's possible to hook the end of the current scope compilation with L.
+
+Some rare oddities may still happen when running inside the debugger.
+It may help to use a perl higher than 5.8.9 or 5.10.0, as they contain some context-related fixes.
+
+Calling C to replace an L'd code frame does not work :
+
+=over 4
+
+=item *
+
+for a C older than the 5.8 series ;
+
+=item *
+
+for a C C run with debugging flags set (as in C) ;
+
+=item *
+
+when the runloop callback is replaced by another module.
+
+=back
+
+In those three cases, L will look for a C statement in its callback and, if there is one, throw an exception before executing the code.
+
+Moreover, in order to handle C statements properly, L currently has to suffer a run-time overhead proportional to the size of the the callback in every case (with a small ratio), and proportional to the size of B the code executed as the result of the L call (including subroutine calls inside the callback) when a C statement is found in the L callback.
+Despite this shortcoming, this XS version of L should still run way faster than the pure-Perl version from L.
=head1 DEPENDENCIES
@@ -269,8 +691,17 @@ L (standard since perl 5.006).
=head1 SEE ALSO
+L, L.
+
L, L, L, L.
+L.
+
+L is a thin wrapper around L that gives you a continuation passing style interface to L.
+It's easier to use, but it requires you to have control over the scope where you want to return.
+
+L.
+
=head1 AUTHOR
Vincent Pit, C<< >>, L.
@@ -279,7 +710,8 @@ You can contact me by mail or on C (vincent).
=head1 BUGS
-Please report any bugs or feature requests to C, or through the web interface at L. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
+Please report any bugs or feature requests to C, or through the web interface at L.
+I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
=head1 SUPPORT
@@ -293,9 +725,11 @@ Tests code coverage report is available at L